Going by the US popularity I have:
Noah Liam (#1 & #2)
Charlotte Sofia (#11 & #13)
Immanuel Lachlan (#993 & #986)
Belén Temperance (#898 & #888)
Going by Croatian popularity:
Luka Ivan (#1 & #2)
Lana Lara (#1 & #11)
Sebastian Adam (#97 & #81)
Lucia Una (#95 & #92)